There is no standard dose of butterbur because no studies have been done on the substance to determine the most effective and safest dosage. Little information is available to guide people in choosing an appropriate dose, so it's best to follow the directions on the product label. Also, it is important to choose a butterbur product made by a reputable manufacturer that does not contain toxic alkaloids.
As is the case with natural products and herbal supplements, there is no clearly established dose of butterbur that is considered safe and effective. As a result, much of the available information on butterbur dosing comes from small clinical studies or from practical experience with the supplement.
There are a few different reasons why it is difficult to recommend a dose of butterbur. Unlike prescription or non-prescription drugs, there is no standard recommended dose for herbal supplements. In addition, there may be significant variability of the content, purity, and strength among different brands of the same herbal supplement, making consistently safe and effective dosing difficult.
For migraine prevention or treatment, some studies have used a butterbur dosage of 50 mg to 100 mg twice daily with meals. These studies used a specific butterbur product (Petadolex®) that is purified to remove toxic alkaloids naturally found in butterbur and standardized to contain a consistent amount of the active components. Another study used a different product (Petaforce®) at a dosage of 50 mg twice daily for the treatment of allergies. It is not known with certainty if these are the safest or most effective doses for butterbur.
Because there is little high-quality information about butterbur dosing and because there may be significant variability in the active component content among various butterbur products, it is a good idea to follow the instructions on the product label.